gma pipe_setup: Replace Update_Offset() with Setup_FB()

Beside updates to the framebuffer offset in memory, Setup_FB() allows
changes to size, position, tiling and rotation, too. Basically every-
thing but changes to BPC (which would need an update in the transcoder
configuration on pre-Broadwell hardware, too).

It is not clear if the updates work fully synchronous on all hardware
generations. Though, tests on APL have shown a glitch free transition
so far.

Change-Id: I3c8352315390d9c4d2fb2a7e09355b5fe4089421
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/23165
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/common/hw-gfx-gma-pipe_setup.adb b/common/hw-gfx-gma-pipe_setup.adb
index 5bcc4c8..4544e73 100644
--- a/common/hw-gfx-gma-pipe_setup.adb
+++ b/common/hw-gfx-gma-pipe_setup.adb
@@ -471,25 +471,34 @@
 
    ----------------------------------------------------------------------------
 
+   procedure Setup_FB
+     (Pipe        : Pipe_Index;
+      Mode        : Mode_Type;
+      Framebuffer : Framebuffer_Type)
+   is
+      -- Enable dithering if framebuffer BPC differs from port BPC,
+      -- as smooth gradients look really bad without.
+      Dither : constant Boolean := Framebuffer.BPC /= Mode.BPC;
+   begin
+      pragma Debug (Debug.Put_Line (GNAT.Source_Info.Enclosing_Entity));
+
+      Setup_Display (Controllers (Pipe), Framebuffer, Mode.BPC, Dither);
+      Setup_Scaling (Controllers (Pipe), Mode, Framebuffer);
+   end Setup_FB;
+
    procedure On
      (Pipe        : Pipe_Index;
       Port_Cfg    : Port_Config;
       Framebuffer : Framebuffer_Type)
    is
-      -- Enable dithering if framebuffer BPC differs from port BPC,
-      -- as smooth gradients look really bad without.
-      Dither : constant Boolean := Framebuffer.BPC /= Port_Cfg.Mode.BPC;
    begin
       pragma Debug (Debug.Put_Line (GNAT.Source_Info.Enclosing_Entity));
 
       Transcoder.Setup (Pipe, Port_Cfg);
 
-      Setup_Display
-        (Controllers (Pipe), Framebuffer, Port_Cfg.Mode.BPC, Dither);
+      Setup_FB (Pipe, Port_Cfg.Mode, Framebuffer);
 
-      Setup_Scaling (Controllers (Pipe), Port_Cfg.Mode, Framebuffer);
-
-      Transcoder.On (Pipe, Port_Cfg, Dither);
+      Transcoder.On (Pipe, Port_Cfg, Framebuffer.BPC /= Port_Cfg.Mode.BPC);
    end On;
 
    ----------------------------------------------------------------------------
@@ -544,15 +553,4 @@
       end loop;
    end All_Off;
 
-   ----------------------------------------------------------------------------
-
-   procedure Update_Offset (Pipe : Pipe_Index; Framebuffer : Framebuffer_Type)
-   is
-   begin
-      pragma Debug (Debug.Put_Line (GNAT.Source_Info.Enclosing_Entity));
-
-      Registers.Write
-        (Controllers (Pipe).DSPSURF, Framebuffer.Offset and 16#ffff_f000#);
-   end Update_Offset;
-
 end HW.GFX.GMA.Pipe_Setup;